1. Field of the Invention
When a person buys a lamp in a retail establishment, it typically comes with a shade affixed. Increasingly, however, the consumer has options, and a lamp base and a shade support are sold separately from the shade, and the consumer then has a choice of many different shades in a variety of shapes and sizes.
The usual support of shades on lamps is referred to as a harp. Harps come in sizes which relate proportionateley to the size of the lamp. When a consumer elects a particular shade as a result of one's personal taste, it may be of a length which does not fit on the harp sold with the lamp. Under such circumstances, the consumer either seeks out a different harp, and they are not exactly easy to locate, or the consumer buys a new shade which is compatible with the existing harp. Neither option is particularly attractive, and it is to that concern that the harp of the present invention is directed.
2. Overview of the Prior Art
The concept of a shade holder that is extensible and retractable is not a new concept. See, for example, Ewing U.S. Pat. No. 1,235,020 which shows a shade holder having a series of upstanding rods which are mounted in support arms and held in a particular position by thumb screws.
While Ewing uses thumb screws which engage the rods and hold them frictionally, Lee, in his U.S. Pat. No. 5,412,554, accomplishes the same result by drilling screw holes in the rods and threading a set screw into one of those holes.
Smurik, in his U.S. Pat. No. 2,593,704, employs yet another means of securing the position of the upper portion of a harp in a predetermined position relative to the lower section, by using finger pieces which insert protuberances in slots in the upper legs of the harp to secure the segments of the harp at a predetermined position.
While accomplishing the same objectives as his forerunners, Leef, U.S. Pat. No. 2,408,522, uses yet another means of choosing and holding the position of the harp at a desired height.
Yet another method of positioning and holding the harp in a predetermined position is found in Auerbach U.S. Pat. No. 1,946,959. Auerbach cut notches in the legs and then uses what he calls “caps” to lock into the notches to hold the harp in place.
There are several others along the same general lines, among them, Berger reissue patent number 20,170; Shoglow U.S. Pat. No. 2,895,941 and Pape et al. U.S. Pat. No. 6,971,773. All of these patents appear to have issued because each uses a different means of securing the harp at the desired height.